Harvard-Westlake Upper School Parking Improvement Plan, Sound Propagation Analysis, Arup, August 20, 2013 (Appendix F.2).

Transcription

1 3.7 NOISE This section provides an overview of noise and vibration levels and evaluates the construction and operational impacts associated with the Proposed Project. Topics addressed include short-term construction and long-term operational noise and groundborne vibration. This section was prepared by Terry A. Hayes Associates Inc. Noise modeling results (updated in 2015) are included in Appendix F.1 Noise Modeling. In addition the following technical study is summarized in the analysis: Harvard-Westlake Upper School Parking Improvement Plan, Sound Propagation Analysis, Arup, August 20, 2013 (Appendix F.2). The following background information provides noise and vibration characteristics and effects. EXISTING CONDITIONS Noise Characteristics and Effects Characteristics of Sound. Sound is technically described in terms of the loudness (amplitude) and frequency (pitch) of the sound. The standard unit of measurement for sound is the decibel (db). The human ear is not equally sensitive to sound at all frequencies. The A-weighted scale, abbreviated dba, reflects the normal hearing sensitivity range of the human ear. On this scale, the range of human hearing extends from approximately 3 to 140 dba. Figure provides examples of A-weighted noise levels from common sounds. Noise Definitions. This noise analysis discusses sound levels in terms of Community Noise Equivalent Level (CNEL) and Equivalent Noise Level (L eq ). Community Noise Equivalent Level. CNEL is an average sound level during a 24-hour period. CNEL is a noise measurement scale, which accounts for noise source, distance, single event duration, single event occurrence, frequency, and time of day. Human reaction to sound between 7:00 p.m. and 10:00 p.m. is as if the sound were actually 5 dba higher than if it occurred from 7:00 a.m. to 7:00 p.m. From 10:00 p.m. to 7:00 a.m., humans perceive sound as if it were 10 dba higher due to the lower background level. Hence, the CNEL is obtained by adding an additional 5 dba to sound levels in the evening from 7:00 p.m. to 10:00 p.m. and 10 dba to sound levels in the night from 10:00 p.m. to 7:00 a.m. Because CNEL accounts for human sensitivity to sound, the CNEL 24-hour figure is always a higher number than the actual 24-hour average. Equivalent Noise Level. L eq is the average noise level on an energy basis for any specific time period. The L eq for one hour is the energy average noise level during the hour. The average noise level is based on the energy content (acoustic energy) of the sound. L eq can be thought of as the level of a continuous noise which has the same energy content as the fluctuating noise level. The equivalent noise level is expressed in units of dba. Effects of Noise. Noise is generally defined as unwanted sound. The degree to which noise can impact the human environment range from levels that interfere with speech and sleep (annoyance and nuisance) to levels that cause adverse health effects (hearing loss and psychological effects). Human response to noise is subjective and can vary greatly from person to person. Factors that influence individual response include the intensity, frequency, and pattern of noise, the amount of background noise present before the intruding noise, and the nature of work or human activity that is exposed to the noise source. Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

2 dba Near Jet Engine 130 THRESHOLD OF PAIN Rock-n-Roll Band Deafening Jet Loud Auto 10ft Power Mower 25ft Food Blender Garbage Disposal Living Room Music Human 3ft Very Loud Loud Residential Air 50ft Bird Calls Moderate Quiet Living Room 30 Faint Average Whisper 20 Rustling Leaves 10 0 Very Faint THRESHOLD OF HUMAN AUDIBILITY SOURCE: Cowan, James P., Handbook of Environmental Acoustics Harvard-Westlake School Parking Structure Figure A-Weighted Decibel Scale

3 Audible Noise Changes. Studies have shown that the smallest perceptible change in sound level for a person with normal hearing sensitivity is approximately 3 dba. A change of at least 5 dba would be noticeable and would likely evoke a community reaction. A 10-dBA increase is subjectively heard as a doubling in loudness and would cause a community response. Noise levels decrease as the distance from the noise source to the receiver increases. Noise generated by a stationary noise source, or point source, will decrease by approximately 6 dba over hard surfaces (e.g., reflective surfaces such as parking lots or smooth bodies of water) and 7.5 dba over soft surfaces (e.g., absorptive surfaces such as soft dirt, grass, or scattered bushes and trees) for each doubling of the distance. For example, if a noise source produces a noise level of 89 dba at a reference distance of 50 feet, then the noise level would be 83 dba at a distance of 100 feet from the noise source, 77 dba at a distance of 200 feet, and so on. Noise generated by a mobile source will decrease by approximately 3 dba over hard surfaces and 4.8 dba over soft surfaces for each doubling of the distance. Generally, noise is most audible when traveling by direct line-of-sight. Line-of-sight is an unobstructed visual path between the noise source and the noise receptor. Barriers, such as walls, berms, or buildings that break the line-of-sight between the source and the receiver greatly reduce noise levels from the source since sound can only reach the receiver by bending over the top of the barrier. Sound barriers can reduce sound levels by up to 20 dba. However, if a barrier is not high or long enough to break the lineof-sight from the source to the receiver, its effectiveness is greatly reduced. Vibration Characteristics and Effects Characteristics of Vibration. Vibration is an oscillatory motion through a solid medium in which the motion s amplitude can be described in terms of displacement, velocity, or acceleration. Vibration can be a serious concern, causing buildings to shake and rumbling sounds to be heard. In contrast to noise, vibration is not a common environmental problem. It is unusual for vibration from sources such as buses and trucks to be perceptible, even in locations close to major roads. Some common sources of vibration are trains, buses on rough roads, and construction activities, such as blasting, pile driving, and heavy earth-moving equipment. Vibration Definitions. There are several different methods that are used to quantify vibration. The peak particle velocity (PPV) is defined as the maximum instantaneous peak of the vibration signal. The PPV is most frequently used to describe vibration impacts to buildings and is usually measured in inches per second. The root mean square (RMS) amplitude is most frequently used to describe the effect of vibration on the human body. The RMS amplitude is defined as the average of the squared amplitude of the signal. Decibel notation (Vdb) is commonly used to measure RMS. The decibel notation acts to compress the range of numbers required to describe vibration. Effects of Vibration. High levels of vibration may cause physical personal injury or damage to buildings. However, groundborne vibration levels rarely affect human health. Instead, most people consider groundborne vibration to be an annoyance that can affect concentration or disturb sleep. In addition, high levels of groundborne vibration can damage fragile buildings or interfere with equipment that is highly sensitive to groundborne vibration (e.g., electron microscopes). To counter the effects of groundborne vibration, the Federal Transit Administration (FTA) has published guidance relative to vibration impacts. Perceptible Vibration Changes. In contrast to noise, groundborne vibration is not a phenomenon that most people experience every day. The background vibration velocity level in residential areas is usually 50 RMS or lower, well below the threshold of perception for humans, which is around 65 RMS. Most perceptible indoor vibration is caused by sources within buildings, such as operation of mechanical equipment, movement of people, or slamming of doors. Typical outdoor sources of perceptible Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

4 groundborne vibration are construction equipment, steel-wheeled trains, and traffic on rough roads. If the roadway is smooth, the vibration from traffic is rarely perceptible. Noise The existing noise environment near the Development Site is characterized by vehicular traffic, activity associated with the Harvard-Westlake School Campus, St. Michael s and All Angeles Church, and Sunnyside Preschool, and residential uses in the vicinity. Sound measurements were taken at a representative sample of residential land uses using a SoundPro DL Sound Level Meter on October 16, 2012 to determine existing noise levels in the Project vicinity. According to the updated Supplemental Traffic Analysis (see Appendix G.2), existing (2015) peak hour traffic counts have declined incrementally at all five study intersections, including the Coldwater Canyon Avenue/Ventura Boulevard intersection, in comparing the 2011 to 2015 traffic count data. This decrease in traffic (of approximately 8% to 15%) would have a negligible effect on noise since, according to the California Department of Transportation Technical Noise Supplement, a doubling or halving of traffic is typically required to generate a 3 dba (or audible) change in noise levels. Therefore, the 2012 noise measurements remain appropriate, and conservative, for this analysis. Daytime measurements were used to establish existing ambient noise conditions and to provide a baseline for evaluating construction impacts and after school measurements were used to assess operational impacts. Noise monitoring locations are shown in Figure As shown in Table 3.7-1, daytime existing ambient sound levels ranged between 50.2 and 69.0 dba L eq and after school sound levels ranged between 44.9 and 68.2 dba L eq. In addition, noise levels were monitored during existing playfield Ted Slavin Field activity to identify the noise levels at the proposed athletic practice field. This is an overly conservative monitoring comparison because unlike Ted Slavin Field, the practice field will have no bleachers, no public address system and will not be used for games. Activity Activities at Ted Slavin Field included football, cross-country, and soccer and the noise level was 52.7 dba L eq at 288 feet, which was the distance from the center of the existing field Ted Slavin Field to the noise monitor. Based on distance attenuation, this was converted into a reference noise level of 70.6 dba at 50 feet. TABLE 3.7-1: EXISTING NOISE LEVELS Key to Daytime Sound Levels After School Sound Levels Figure Noise Monitoring Location (dba, L eq ) (dba, L eq ) Southern End of Football Ted 1 Slavin Field Coldwater Canyon Avenue Avenue Del Sol Galewood Street Potosi Avenue Drive SOURCE: TAHA, Vibration There are no stationary sources of vibration located near the Development Site. Heavy-duty trucks can generate groundborne vibrations that vary depending on vehicle type and weight, and pavement conditions. Vibration from adjacent roadways are not typically perceptible at the Development Site. Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

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6 Sensitive Receptors Noise- and vibration-sensitive land uses are locations where people reside or where the presence of unwanted sound could adversely affect the use of the land. Residences, schools, hospitals, guest lodging, libraries, and some passive recreation areas would each be considered noise- and vibration-sensitive and may warrant unique measures for protection from intruding noise. As shown in Figure 3.7-2, sensitive receptors near the Development Site include residences, and Sunnyside Preschool. At the same address as the Sunnyside Preschool is St. Michael s Church (which includes the Sunnyside Preschool). The analysis in this report focuses on the impact of the Project on the Preschool rather than the church because church activities are mainly on weekday evenings and Sunday and would therefore not be impacted by construction. (There would be no construction on weekends and only limited athletic activity occurs on Sundays). These sensitive receptors represent the nearest sensitive receptors with the potential to be significantly impacted by the Proposed Project. Additional sensitive receptors are located in the surrounding community within one-quarter mile of the Development Site and may be impacted by the Proposed Project but to a lesser extent. REGULATORY FRAMEWORK Noise Noise Element of the General Plan. The City has developed a Noise Element of the General Plan to guide in the development of noise regulations. 1 It addresses noise mitigation regulations, strategies and programs and delineates Federal, State and City jurisdiction relative to rail, automotive, aircraft and nuisance noise. Programs included in the Noise Element that are relevant to the Proposed Project include: For a proposed development project that is deemed to have a potentially significant noise impact on noise sensitive uses, as defined by this chapter, require mitigation measures, as appropriate, in accordance with California Environmental Quality Act and City procedures. Use, as appropriate, the Guidelines for Noise Compatible Land Use (Table 3.7-2), or other measures that are acceptable to the City, to guide land use and zoning reclassification, subdivision, conditional use and use variance determinations and environmental assessment considerations, especially relative to sensitive uses, as defined by this chapter, within a CNEL of 65 db airport noise exposure areas and within a line of sight of freeways, major highways, railroads or truck haul routes. (It is estimated that the existing CNEL, which is a 24-hour average, in the project area is approximately 48.3 dba). City of Los Angeles Municipal Code Noise Regulations. The City of Los Angeles has established policies and regulations concerning the generation and control of noise that could adversely affect its citizens and noise sensitive land uses. Los Angeles Municipal Code (LAMC) Section (Noise Due to Construction, Excavation Work When Prohibited) indicates that no construction or repair work shall be performed between the hours of 9:00 p.m. and 7:00 a.m., since such activities would generate loud noises and disturb persons occupying sleeping quarters in any adjacent dwelling, hotel, apartment or other place of residence. No person, other than an individual home owner engaged in the repair or construction of his/her single-family dwelling, shall perform any construction or repair work of any kind or perform such work within 500 feet of land so occupied before 8:00 a.m. or after 6:00 p.m. on any Saturday or on a federal holiday, nor at any time on any Sunday. Under certain conditions, the City may grant a waiver to allow limited construction activities to occur outside of the limits described above. 1 City of Los Angeles, Noise Element of the Los Angeles City General Plan, February 3, Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

7 TABLE 3.7-2: GUIDELINES FOR NOISE COMPATIBLE LAND USE Land Use Category Residential - Low Density Single-Family, Duplex, Mobile Homes Community Noise Exposure (dba, CNEL) Residential - Multi-Family Transient Lodging - Motels Hotels Schools, Libraries, Churches, Hospitals, Nursing Homes Auditoriums, Concert Halls, Amphitheaters Sports Arena, Outdoor Spectator Sports Playgrounds, Neighborhood Parks Golf Courses, Riding Stables, Water Recreation, Cemeteries Office Buildings, Business Commercial and Professional Industrial, Manufacturing, Utilities, Agriculture Normally Acceptable - Specified land use is satisfactory, based upon the assumption that any buildings involved are of normal conventional construction without any special noise insulation requirements. Conditionally Acceptable - New construction or development should be undertaken only after a detailed analysis of the noise reduction requirements is made and needed noise insulation features included in the design. Conventional construction, but with closed windows and fresh air supply system or air conditioning will normally suffice. Normally Unacceptable - New construction or development should generally be discouraged. If new construction or development does proceed, a detailed analysis of the noise reduction requirements must be made and needed noise insulation features included in the design. Clearly Unacceptable - New construction or development should generally not be undertaken. SOURCE: California Office of Noise Control, Department of Health Services. Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

8 LAMC Section (Maximum Noise Level of Powered Equipment or Powered Hand Tools) also specifies the maximum noise level of powered equipment or powered hand tools. Any powered equipment or hand tool that produces a maximum noise level exceeding 75 dba at a distance of 50 feet is prohibited. However, this noise limitation does not apply where compliance is technically infeasible. Technically infeasible means the above noise limitation cannot be met despite the use of mufflers, shields, sound barriers and/or any other noise reduction device or techniques during the operation of equipment. City of Los Angeles Municipal Code Zoning Regulations. The City s planning and zoning code (LAMC Section 11 et seq.) contains a variety of provisions that directly or indirectly mitigate noise impacts on or impacts that are associated with, different types of land uses. Permit processing is guided by the General Plan, especially the community plans which together are the City s Land Use Element. The plans designate appropriate land use (zoning) classifications. The noise ordinance guides land use considerations by setting maximum ambient noise levels for specific zones. Conditional use permits (LAMC Section 12.24) allow the City to assess potential use impacts and impose conditions to mitigate noise impacts. Conditional use permits are required in certain zones for various land uses including, but not limited to, schools, churches, alcohol sales, parks, mixed-use development, and automobile repair facilities. In most cases the uses are allowed-by-right in less restrictive zones. Some are prohibited entirely in residential zones. The permitting procedures include site investigations, notice to neighbors and hearings to assist decision makers in determining if the use should be permitted and, if permitted, allow the imposition of appropriate conditions of approval. Typical conditions include specific site design, setbacks, use limitations on all or parts of the site, walls and hours of operation so as to minimize noise and other impacts. The authority to revoke, discontinue a use or to impose nuisance abatement conditions on established uses has become a major tool for reducing nuisance noise. Use permits may be revoked by the City for nuisance (including disturbance of the peace) or noncompliance with conditions of a conditional use permit. In addition, the City may impose operational conditions on existing commercial or industrial uses that are deemed a nuisance, including for excessive noise or disturbance of the peace (LAMC Section A.15). These two procedures have been increasingly utilized in recent years to encourage owners to operate activities on their properties in a manner that is compatible with adjacent uses, particularly residential uses. Vibration There are no adopted City or State standards for vibration. Table shows Federal guidelines for vibration damage criteria. These criteria are based on the type of building construction. Single family residential buildings typically are non-engineered timber and masonry buildings and can be exposed to 0.2 inches per second PPV without experiencing damage. Vibration is a localized impact within a few feet of construction activity. Neither the St. Michael s Church nor the Sunnyside Preschool are sufficiently close to the construction activity to experience any vibrations from the Project. TABLE 3.7-3: VIBRATION DAMAGE CRITERIA Building Category PPV (Inches Per Second) I. Reinforced-concrete, steel, or timber (no plaster) 0.5 II. Engineered concrete and masonry (no plaster) 0.3 III. Non-engineered timber and masonry buildings 0.2 IV. Buildings extremely susceptible to vibration damage 0.12 SOURCE: Federal Transit Administration, Transit Noise and Vibration Impact Assessment, May Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

9 THRESHOLDS OF SIGNIFICANCE In accordance with Appendix G of the State CEQA Guidelines, the a proposed project would have a significant impact related to noise if it would: Expose persons or generate noise in levels in excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies; Expose people to or generate excessive groundborne vibration or groundborne noise levels; Result in a substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project; and/or Result in a substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project. The City of Los Angeles has established significance thresholds in its L.A. CEQA Thresholds Guide. The following specific significance thresholds are relevant to the Proposed Project: Construction Noise. A significant impact related to construction activity would occur if: Construction activities lasting more than one day would exceed existing ambient exterior noise levels by 10 dba or more at a noise sensitive use; Construction activities lasting more than ten days in a three-month period would exceed existing ambient noise levels by 5 dba or more at a noise sensitive use; or Construction activities would exceed the ambient noise level by 5 dba at a noise sensitive use between the hours of 9:00 p.m. and 7:00 a.m. Monday through Friday, before 8:00 a.m. or after 6:00 p.m. on Saturday, or anytime on Sunday. Operational Noise. A significant impact related to operational activity would occur if: Ambient noise level measured at the property line of the affected uses increase by 3 decibels CNEL to or within the normally unacceptable or clearly unacceptable category, or any 5 dba or greater noise increase, (see Table 3.7-2). Vibration. There are no adopted State or City of Los Angeles vibration standards. Based on Federal guidelines, a significant impact related to operational activity of the Project would occur if: Construction-related vibration levels would The Project would generate vibration than exceed 0.2 inches per second PPV at residential land uses. IMPACTS Construction Noise Equipment Noise. Construction of the Proposed Project would result in temporary increases in ambient noise levels in the Project area on an intermittent basis. The increase in noise would occur during the approximate month construction schedule. Noise levels would fluctuate depending on the construction phase, equipment type and duration of use, distance between the noise source and receptor, and presence or absence of noise attenuation barriers. Construction activities typically require the use of numerous pieces of noise-generating equipment. Typical noise levels from various types of equipment that may be used during construction are listed in Table The table shows noise levels at distances of 50 and 100 feet from the construction noise source. The Proposed Project would include soil nailing to stabilize the slope construct the retaining walls at the Development Site. The soil nailing technique Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

10 involves the insertion of relatively slender reinforcing elements into the slope and it generates a noise level similar to an auger drill. TABLE 3.7-4: MAXIMUM NOISE LEVELS OF COMMON CONSTRUCTION EQUIPMENT Noise Level (dba) Noise Source 50 Feet 100 Feet Front Loader Trucks Cranes (derrick) Back Hoe Tractor Scraper/Grader Paver Auger Drilling Air Compressor Excavator Dozer Concrete Pump Compactor Roller SOURCE: City of Los Angeles, L. A. CEQA Thresholds Guide, 2006 and Table 9.9, Chapter 12 of the FTA Transit Noise and Vibration Guidance Handbook, May The noise levels shown in Table take into account the likelihood that more than one piece of construction equipment would be in operation at the same time and lists the typical overall noise levels that would be expected for each phase of construction. The highest noise levels are expected to occur during the grading/excavation and finishing phases of construction. A typical piece of noisy equipment is assumed to be active for 40 percent of the eight-hour workday, In the absence of a specific construction plan, this assumption is consistent with the USEPA studies of typical construction operations and associated construction noise, generating a noise level of 89 dba L eq at a reference distance of 50 feet. The phases of construction include grading (234 days), soil nailing (234 days), shotcrete (234 days), foundation/structure (338 days), tower/ramp construction (130 days), sitework (156 days), streetwork (26 days), and bridge construction (104 days). During construction of the Project, different activities (phases) would overlap. The highest noise levels are expected to occur during overlap of grading, soil nailing, and shotcrete activities generating a noise of 95.8 dba at 50 feet as a result of overlapping activities. Grading would extend for about 9 months, and for the first 2 months of construction would be the primary activity. Soil nailing and shotcrete activities (associated with construction of retaining walls) would begin in the 3 rd and 4 th months, respectively, and each would continue for a duration of approximately 9 months overlapping for 6 to 7 months with grading activities. Following site grading, soil nails and shotcrete, there would be approximately 13 months of foundations and structure work (that would occur within the Parking Structure footprint only) that would overlap with first about 5 months of work on the tower/ramp and then by about 4 months of work on the bridge. Site work and street work would not overlap with other activities. Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

11 TABLE 3.7-5: OUTDOOR CONSTRUCTION NOISE LEVELS Construction Phase Noise Level at 50 Feet (dba) Ground Clearing 84 Grading/Excavation 89 Foundations 78 Structural 85 Finishing 89 Site Preparation 86 Grading and Retaining Walls 94 Soil Nailing 88 Shotcrete 87 Foundation/Structure and Tower/Ramp 92 Street Work 83 Bridge 88 Site Work 92 SOURCE: City of Los Angeles, L.A. CEQA Thresholds Guide, 2006 and Table 9.9, Chapter 12 of the FTA Transit Noise and Vibration Guidance Handbook, May The noise level during the construction period at each receptor location was calculated by (1) making a distance adjustment to the construction source sound level and (2) logarithmically adding the adjusted construction noise source level to the ambient noise level. These calculations and the estimated noise levels are presented in Appendix F.1. Table identifies the location (by street) and number of significantly impacted sensitive receptors during the most impactful phase of construction (grading overlapping with soil nailing and shotcrete). Figure shows the location of these significantly impacted receptors. (Not included in this analysis or in Table or Figure are residences owned by the Harvard-Westlake School and the Harvard-Westlake School itself.) Figure shows distance contours from the construction limit lines. Houses closest to the construction would experience the highest increase in noise levels. It is difficult to accurately predict the noise levels at each residence due to the complex terrain associated with the Santa Monica Mountains as well as intervening structures (trees and plant materials have limited effects on noise). It was generally assumed that terrain features that block the line-of-sight from the receptor to the construction area would decrease noise levels by 10 to 15 dba. A sound transmission analysis (see Appendix F.2) was conducted to study potential echoing affects associated with topography in the area of the Development Site. Eight loudspeakers in a hemispherical configuration (the test noise source) were connected to an electronic noise generator capable of producing a maximum 104-dBA sound level, 10 feet from the face of the loudspeakers. The loudspeakers were set up in a hemispherical arrangement to characterize potential reflections from topography and structures. The hemispherical configuration of the sound source provided sound transmission in all directions that would allow reflected sound waves, if present, to be detected at the receiver locations. Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

12 TABLE 3.7-6: UNMITIGATED CONSTRUCTION NOISE SIGNIFICANTLY IMPACTED RESIDENCES, ST. MICHAEL'S CHURCH AND SUNNYSIDE PRESCHOOL Street/ Receptor Number of Significantly Impacted Receptors Galewood Street 6 8 Van Noord Avenue 2 4 Blairwood Drive 4 7 Potosi Avenue Drive 2 3 Avenida Del Sol Alta Mesa Drive St. Michael 's Church and Sunnyside Preschool Distance from Construction Limit Line to Property Line (feet) /a/ Maximum Construction Noise Level (dba) /b/ Existing Ambient (dba L eq ) /c/ Temporary New Ambient (dba L eq ) /d/ /a/ Distance of noise source from receptor. The distance is from the construction limit line to the property line. /b/ Construction noise source s sound level at receptor location with distance and building adjustment as applicable. /c/ Pre-construction activity ambient sound level at receptor locations. /d/ New sound level at receptor location during the construction period, including noise from construction activity. SOURCE: TAHA, ; see Appendix F.1 a) Construction Noise Level Calculations Range of Noise Increases The study included 14 receiver locations around the Development Site, at representative locations east and west of Coldwater Canyon Avenue. The sound transmission tests and analysis show there are no significant sound reflections (defined as being within 10 db of the direct sound), from local topography or neighboring buildings at the surrounding receptor locations. Construction noise levels would exceed the 5-dBA incremental increase significance threshold at approximately residences, including along Avenida del Sol, Alta Mesa Boulevard, at the ends of Van Noord Avenue, Blairwood Drive, Potosi Drive Avenue, and Galewood Street nearest to the Development Site. There would also be a significant increase in noise during construction at St. Michael's Church and Sunnyside Preschool. Therefore, without mitigation, the Proposed Project would result in a significant impact related to construction noise. The analysis presented above identifies maximum noise levels associated with all construction activity including all activities at the construction limits (such as within the school Harvard-Westlake Campus driveway, debris basin, retaining walls, and construction of the north retaining wall north along Coldwater Canyon Avenue). Construction activity within the Harvard-Westlake Campus main entrance driveway would impact residences along Avenida del Sol and Alta Mesa Drive Boulevard Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

13 N VA R O O N D O O RW DR A LE W O O D ST A LT A M E S A D AV EN R ID A D EL SO L BLA IRW OO DD R E AV AI D BL G LD CO DA DEL E AV NI AVE N YO AN RC TE WA PO TO SI AV E SOL AL TA M ES A AVE TE OES DR N LEGEND: Construction Limits Approx. Scale Parking Structure and Retaining Wall Footprint Construction Impact Measured from the Construction Limits Feet Harvard-Westlake School Parking Structure SOURCE: Google Earth and TAHA, Figure Unmitigated Construction Noise Impacts

14 N VA O O N R D O O RW AI BL D E AV DR G A LE DR W O ST ON NY CA FE ET 90 0 FE ET FE ET PO TO SI AV E 50 0F EE T 70 0 D S A FE ET OL EL S AD NID AVE 30 0 E AV 0 M E A LT A R TE WA AV EN ID A LD CO 10 R D EL SO L BLA IRW OO D O D AL TA M ES A TE OES DR AVE Note: These contours strictly represent distances from the construction limit. The impact distances vary depending on existing ambient noise levels and topographical features. N Approx. Scale LEGEND: Construction Limits foot Intervals from Construction Boundary Feet Harvard-Westlake School Parking Structure SOURCE: Google Earth and TAHA, Figure Construction Distance Contours

15 Construction of the retaining wall at the northern tip of the Development Site would impact residences at the eastern end of Van Noord Avenue where it intersects Coldwater Canyon Avenue. Construction of the Parking Structure would include grading and building activities for a much longer duration (24 30 months) and would significantly impact residences on Potosi Drive Avenue, Blairwood Avenue, and Galewood Avenue and St. Michael s Church/Sunnyside Preschool. Impacted Residences, and the Sunnyside Preschool, Sensitive receptors that would be significantly impacted by construction activities are shown in Figure While noise levels would not exceed thresholds at other locations, some receptors (people in nearby homes in addition to those identified as significantly impacted) would be able to hear construction noise and may be impacted to a less than significant level. Assuming wood frame construction, in general, it is anticipated that interior speech would not be interfered with at adjacent residences; however construction activity could disrupt daytime sleepers. This potential disruption would be short-term and intermittent and could likely be avoided in some rooms of the house away from the construction site Development Site if rooms are sufficiently far away and/or insulated. Truck Noise. During peak construction activity, it is anticipated that ten haul truck trips per hour (i.e., five inbound trips and five outbound trips) trucks would travel Coldwater Canyon Avenue between the Development Site and the Ventura Freeway. Harvard-Westlake School would limit hauling to incidental deliveries during the 8:00 a.m. to 9:00 a.m. hour, 12 truck trips (6 inbound trips and 6 outbound trips) during the 9:00 a.m. - 10:00 a.m. hour and the 3:00 p.m. to 4:00 p.m. hour, 28 truck trips (14 inbound trips and 14 outbound trips) during 10:00 a.m. and 2:00 p.m., and 24 truck trips (12 inbound trips and 12 outbound trips) during the 2:00 p.m. to 3:00 p.m. hour. (Soil nailing would include 3 trucks per day, spaced out over 5 hours and shotcrete would include 5 trucks per day, spaced out over 5 hours.) On Saturdays, up to 160 daily truck trips are also anticipated (6-hour workday, from 10:00 a.m. to 4:00 p.m., with up to 28 truck trips per hour). Table presents the estimated noise levels for each time period at sensitive receptors located along the haul route. As shown in this table, truck activity would not generate noise levels that exceed the 5-dBA incremental increase significance threshold. Therefore, the Proposed Project would result in a less-than-significant impact related to truck noise. TABLE 3.7-7: OFF-SITE CONSTRUCTION HAUL TRUCK NOISE LEVELS Scenario and Roadway Segment AM Peak Hour Baseline (dba L eq ) Construction (dba L eq ) Increase (dba L eq ) Coldwater Canyon Ave. between Ventura Freeway and Moorpark St Coldwater Canyon Ave. between Moorpark St. and Ventura Blvd Coldwater Canyon Avenue south of Ventura Boulevard Weekday Afternoon (2:00 or 3:00 p.m.) Coldwater Canyon Ave. between Ventura Freeway and Moorpark St Coldwater Canyon Ave. between Moorpark Street and Ventura Blvd Coldwater Canyon Ave. south of Ventura Blvd Saturday Coldwater Canyon Ave. between Ventura Freeway and Moorpark St Coldwater Canyon Ave. between Moorpark St. and Ventura Blvd Coldwater Canyon Ave. south of Ventura Blvd SOURCE: TAHA, ; see Appendix F.1 a) Construction Noise Level Calculations. Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

16 Vibration Typical vibration levels associated with construction equipment are provided in Table Heavy equipment (e.g., a large bulldozer) generates vibration levels of inches per second PPV at a distance of 25 feet. Soil nailing would generate vibration levels similar to caisson drilling. The closest residential structure not owned by Harvard-Westlake is about feet from the construction limit line on the Development Site. The maximum vibration level at this distance would be less than 0.01 inches per second PPV. Construction vibration would not exceed the 0.2 inches per second PPV at any residential structure (St Michael s Church/Sunnyside Preschool would not be significantly impacted by vibration because of its distance from the construction activity). Therefore, the Proposed Project would result in a less-than-significant impact related to construction vibration. TABLE 3.7-8: VIBRATION VELOCITIES FOR CONSTRUCTION EQUIPMENT Equipment PPV at 25 feet (Inches/Second) Large Bulldozer Caisson Drilling Loaded Trucks Jackhammer Small Bulldozer SOURCE: Federal Transit Administration, Transit Noise and Vibration Impact Assessment, May Operations Noise Parking Structure Noise. Parking structure The operation of the Parking Structure would periodically result in noise events associated with car alarms, car horns, slamming of car doors, engine revs, and tire squeals. Automobile movements would generate a noise level of approximately 58.1 dba L eq at a distance of 50 feet. The Proposed Project includes 750 enclosed parking spaces within the three-floor 3- story (4 level) structure. As shown in Table 3.7-9, parking activity would not generate noise levels that exceed 3 dba L eq. A 24-hour analysis was also completed for the Parking Structure. The Parking Structure activity would result in an incremental increase in the 24-hour average noise levels from 48.3 dba CNEL to 48.6 dba CNEL directly adjacent to the Parking Structure. This negligible increase in CNEL would be well under the 5 dba CNEL incremental increase significance threshold applicable to this area where homes are in the normally acceptable range of noise levels for single-family homes (noise level ranges are shown in Table 3.7-2). Therefore, the Project would result in a less-thansignificant impact related to parking activity. Athletic Practice Field Noise. The Proposed Project would include a rooftop athletic practice field to serve as an accessory use to the Harvard-Westlake School. The athletic field does not include amplified program sound (i.e., music or spoken sound broadcast through a loudspeaker system), thereby minimizing noise impacts. The noise level at the rooftop athletic practice field was determined based on the existing ambient noise level at the existing campus athletic field (Ted Slavin Field) and making a distance adjustment to the measured athletic practice field source sound level. It is estimated that the rooftop athletic practice field would generate a noise level of approximately 70.6 dba L eq at a distance of 50 feet. This is a conservative assumption since the practice field estimated noise level was derived from Ted Slavin Field, and, unlike Ted Slavin Field, the practice field would have no bleachers, public address system, or games. Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

17 TABLE 3.7-9: PARKING STRUCTURE NOISE LEVELS Distance from Parking Structure to Property Line (feet) /a/ Maximum Noise Level (dba) /b/ Existing Ambient (dba L eq ) /c/ New Ambient Sensitive Receptor (dba L eq ) /d/ W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street N. Van Noord Avenue N. Van Noord Avenue N. Van Noord Avenue N. Van Noord Avenue N. Van Noord Avenue W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive Potosi Drive Avenue Potosi Drive Avenue Potosi Drive Avenue Potosi Drive Avenue Potosi Drive Avenue Potosi Drive Avenue Halkirk Street St. Michael's Church and Sunnyside Increase /e/ Preschool Residences on Longridge Avenue 1, /a/ Distance of noise source from receptor. The distance is from the parking structure Parking Structure to the property line. /b/ Parking activity sound level at receptor location with distance and building adjustment. /c/ Pre-operational activity ambient sound level at receptor location. /d/ New sound level at receptor location including parking activity. /e/ An incremental noise level increase of 5 dba [averaged over the day (CNEL)] or more would result in a significant impact. Noise levels shown here are more conservative since they show noise levels for the period of use, not a 24-hour day. SOURCE: TAHA, ; see Appendix F.1 b) Operational Noise Level Calculations Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

18 As shown in Table , athletic practice field activity would generate noise levels less than a 5-dBA incremental time-averaged (L eq ) increase at all residences not owned by the Harvard-Westlake School except for the closest houses on Galewood Street and Blairwood Drive. 2 During athletic activities, the maximum noise increase associated with field activity (averaged over activity periods) is estimated to be approximately 6.6 dba L eq at these residences closest house on Galewood Street. This noise level associated with athletic activity would fluctuate throughout the day as the intensity of activity on the field fluctuates. Although field noise levels would intermittently exceed 5 dba L eq at the nearest residences, the City s of Los Angeles significance criteria requires a 24-hour noise analysis to determine the significance of impacts. On a 24-hour basis, it is estimated that the existing CNEL in the Project area of the Development Site is approximately 48.3 dba. With the Project it is anticipated that the CNEL with athletic practice field noise would increase to approximately dba CNEL at the closest houses on Galewood Street and Blairwood Drive. Therefore, athletic practice field activity would increase the existing CNEL by approximately dba at the closest homes not owned by Harvard-Westlake, which would not exceed the 5 dba CNEL significance threshold (which is the appropriate threshold since the resultant noise level would be compatible with single-family residential use). Houses adjacent to the Development Site are located in residential neighborhoods without substantial noise sources (e.g., freeways or airports); the existing (and calculated future with Project) CNELs are within the acceptable ambient noise range for single-family residential use (see Table for identification of noise levels compatible with different types of land use). Certain activities (e.g., whistles and shouting) would generate noise that would be audible at the exterior of homes in the area. Whistles typically generate an instantaneous maximum noise level ranging between 66.7 dba to 73.1 dba at a distance of 50 feet. The high pitch of whistle noise would be audible at surrounding land uses and could disturb daytime sleepers and could result in an annoyance to residents in the area. The subjective nature of annoyance means that there are large differences between individuals some will have a negative reaction to a sound that others accept or even like. The severity of the noise annoyance is dependent on the regularity of the noise source. Because athletic practice field activity would not significantly impact CNEL (or interior noise levels) at even the closest houses on Galewood Street and Blairwood Drive, impacts to exterior noise levels are considered less than significant according to the City s of Los Angeles significance criteria. Therefore, the Proposed Project would not result in a significant impact related to athletic field noise levels. Combined On-Site Noise. An analysis was also completed to assess the potential combined noise impacts of activities associated with the athletic practice field and parking activities in the structure Parking Structure. Table presents the combined on-site noise levels. The maximum combined incremental average noise level increase that would occur at the closest residences (not owned by the Harvard-Westlake School) on Galewood Street and Blairwood Drive would be 6.8 dba L eq (during times when both athletic practice field activities are under way and parking activities are occurring). This 6.8 dba increase in noise levels would be for the times when activities are occurring in the Parking Structure and on the athletic practice field (Leq). In order to compare noise increases to the City s 5 dba CNEL threshold, the noise levels must be analyzed within the context of a 24-hour day in order to identify the CNEL. 2 The home at the end of Potosi Drive (3680) is owned by Harvard-Westlake and would experience athletic field noise levels greater than 5dBA Leq. Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR

19 TABLE : ATHLETIC PRACTICE FIELD NOISE LEVELS Distance from Athletic Practice Field to Property Line (feet) /a/ Maximum Noise Level (dba) /b/ Existing Ambient (dba, L eq ) /c/ New Ambient Increase Sensitive Receptor (dba, L eq ) /d/ /e/ W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street W. Galewood Street N. Van Noord Avenue N. Van Noord Avenue N. Van Noord Avenue N. Van Noord Avenue N. Van Noord Avenue W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive W. Blairwood Drive Potosi Drive Avenue Potosi Drive Avenue Potosi Drive Avenue Potosi Drive Avenue Potosi Drive Avenue Potosi Drive Avenue Haikirk Street St. Michael's Church and Sunnyside Preschool Residences on Longridge Avenue /a/ Distance of noise source from receptor. The distance is from the athletic practice field to the property line. /b/ Athletic field Practice field activity sound level at receptor location with distance and building adjustment. /c/ Ambient sound level at receptor location prior to proposed activity on the Development Site. /d/ New sound level at receptor locations on completion of the project Project, including noise from the athletic practice field activity. /e/ An incremental noise level increase of 5 dba [averaged over a 24-hour day (CNEL)] or more would result in a significant impact. Noise levels shown here are more conservative since they show noise levels averaged over the period of use of the parking structure, not a 24-hour day. SOURCE: TAHA, ; see Appendix F.1 b) Operational Noise Level Calculations Harvard-Westlake Parking Improvement Plan Recirculated Draft EIR